Information system for road traffic

ABSTRACT

Information system for a traffic network ( 1 ). Information of importance to travellers is transmitted by a transmitter system ( 3 ) to data receivers (pagers) in vehicles ( 2 ) making use of the traffic network. The traffic network is broken down into information regions ( 6 ). The transmitter system transmits information modules ( 5 ) which each relate to an information region and which are characterised by a region-identification code (ID 1,  ID 2  etc.). The information system comprises means for transmitting, upon entry by a vehicle of an information region, to the data receiver in said vehicle the region-identification code of said region, the data receiver setting itself using said region-identification code for receiving information characterised by said region-information code, transmitted by the transmitter system. The region-identification code in the data receiver may be set using regional or local beacon transmitters ( 4 ) which transmit one or two region-identification codes.

BACKGROUND OF THE INVENTION

The invention relates to an information system for a traffic network,information of interest for travellers being transmitted, by atransmitter system, to data receivers in vehicles making use of thetraffic network.

Such a system is disclosed in WO-90/05969, in which the trafficintensity of road sections is measured using infrared detectors and saidinformation, after having been processed, is transmitted to pagerslocated in vehicles. On said pagers, the traffic intensity of the regionis then shown using a graphic display on which the regional road networkis shown, as well as the traffic intensity on the various roads.Although the known system gives an impetus to informing road users, thesystem does not extend beyond a specific region. Although the “region”may of course be chosen large, the consequence then is that theinformation becomes less specific for each road user.

SUMMARY OF THE INVENTION

The invention provides for a system as indicated hereinabove in which,however, the information may be transmitted more specifically to eachroad user, while the system is still usable over a large area (national,European).

The present invention represents a system with which said regionaldistribution of information may be carried out in such a way that foreach user the relevant information travels along with him, as it were.For this purpose, the invention provides for means by which the pagerused by the traveller for (inter alia) receiving traffic information, isautomatically switched from one to the other “information region”. Thetraffic network according to the invention is broken down intoinformation regions having a regional (pager) identification code (RIC)each, and means to provide pagers (in a vehicle), upon entry into a newregion, with the RIC in force for said new region. In doing so, ofcourse, use must be made of (modern) pagers which are suitable forsetting the RIC by an external code signal. Said type of pager iscapable of receiving and displaying messages which are addressed to the(an) individual pager ID [=identifier], but also messages which areaddressed to a collective ID, as a result of which one and the samemessage may be simultaneously passed along to various pagers. Pagerswith which said collective ID is capable of being set from the outsidemay be used in the system according to the invention. The collective IDis preferably set using beacon transmitters.

EXEMPLARY EMBODIMENT

FIG. 1 schematically shows an exemplary embodiment of the invention.Along a motorway 1 there are driving cars 2, provided with pagers, ofwhich only the antennae are visible in the drawing. Information may betransmitted to the pagers by way of a transmitter system 3 (of which onetransmitter is drawn).

The pagers each have an individual ID code to which only said one pagerresponds, but also at least one ID code—a collective ID code—which isnot unique and to which, therefore, various pagers may respond. Pagerswhich are set for receiving such a collective code may—after they havedetected said collective ID code—receive a subsequent message and showit on a display. In addition, modern pagers have the option ofreceiving, by way of a special “system channel” which may be accessedusing a special ID code, one or more other (collective) ID codes. Thereare also pagers with which ID codes nay be set by way of a separatesystem channel, bypassing the information receiver and making use, e.g.,of “RF tagging” [RF=radio-frequency] techniques, transponders etc. Theinvention makes use of this type of modern pager. In order to enablemotorists by way of their pagers to receive information which isrelevant to the road section on which they are driving, there areinstalled local beacon transmitters 4 along the roads. Said beacontransmitters 4 (of which only one has been drawn, but of which there area great number throughout the entire road network) by way of the systemchannel transmit to the pagers of passing motorists the ID code which isused for the distribution of information along the road section in thevicinity of said beacon transmitter 4. The beacon transmitters 4themselves may work in standalone mode and need not themselves beconnected to an information network: they need only transmit one or twocodes—the ID code which is in force for the road section where thebeacon transmitter is located and possibly the ID code of the systemchannel. The beacon transmitters may be fed by the public power grid orusing solar cells.

For the system of beacon transmitters, there are several options. Thearea to which a beacon transmitter relates is entirely covered by saidbeacon transmitter; the beacon transmitter is located in the middle ofthe region. All pagers in the region receive the ID code for said regionfrom the beacon transmitter. Said option is illustrated in FIG. 3.Another option is that each beacon transmitter has only a very limitedpower and is located on the boundary of the region. This is illustratedin FIGS. 5 and 7 which, together with FIGS. 6 and 8, will be discussedin more detail.

The information proper is transmitted by the transmitters 3. Of suchtransmitters 3, too, there are various, though much fewer than thenumber of beacon transmitters 4. The transmitters 3 therefore transmitinformation relating to the various road sections by way of various“information channels”, each channel having its own ID code; therefore,there is a coupling between the road-section-bound ID code and theroad-section-bound information.

Suppose, a motorist passes beacon transmitter 4. Said transmittertransmits the ID code of the system channel and the ID code in force forsaid beacon transmitter and for the road section where it is located.After the pager of the beacon transmitter receives the ID code of thesystem channel, it receives the ID code associated with the road sectionand sets itself to receiving information by way of said ID code. As soonas the transmitter 3, therefore, transmits information using saidroad-section ID, the pager passes said information on to the motorist.The pager ignores the information transmitted by the transmitter 3relating to other road sections as, after all, said information istransmitted by way of channels having other ID codes relevant to otherroad sections.

As soon as the motorist passes a subsequent beacon transmitter, thepager again detects the system-channel ID and a new ID code. The pagerthen sets itself to receiving the channel associated with said ID code,as a result of which the motorist receives, from the transmitter(s) 7,the information which is relevant to the road section on which he isthen driving. FIG. 2 illustrates the transmission, by a transmitter 3 ofthe information-transmitter system, of a series of information modules5. Each of these comprises a header having an identification code (ID1,ID2, ID3 etc.) and a data field (data1, data2, data3 etc.). The datacomprises information on various information regions, as indicated inFIG. 3 by 6 a, 6 b, 6 c etc. Apart from the information regions 6, FIG.3 also shows the course of several motorways 1. The information relatingto the traffic situation on the road sections intersecting with theinformation regions is transmitted by the transmitter system 3. In orderto achieve that the pagers (data receivers) in the cars pass on only theinformation which is relevant to the region where the car is located,the data receiver is “tuned” to messages preceded by an ID code (ID1 orID2 or ID3 etc.) which is in force for said region. For example, in thetransmitter system (or in the information centre which makes use of thetransmitter system) it is determined that messages which are relevant tothe region 6 a are preceded by ID1, messages for region 6 b by ID2,messages for 6 c by ID3 etc. The data receivers in passing cars are set,using the beacon transmitters 4 a . . . g, to the transmission of onlythose messages which are preceded by the ID code of the region of whichthe beacon transmitter is the centre. Thus, beacon transmitter 4 a setsthe pagers of cars entering the region 6 a to receiving messages whichare preceded by ID1. As soon as a car enters region 6 b and its pagercomes within the sphere of influence of beacon transmitter 4 b (i.e.,when the field intensity of the signal received from 4 b is greater thanthe one from 4 a), the pager is switched over from receiving messageshaving ID1/data1 to receiving messages having ID2/data2.

It should be noted that the beacon transmitters 6 may work in standalonemode. In the option shown in FIG. 3, where the beacon transmitters arethe centre of a region, the transmitting power must be relatively large.In addition, it must be prevented, by using a correct frequencyallocation, that there takes place reciprocal interference, orinterference with other systems (e.g., GSM). It is possible, though, inthis option to combine the beacon transmitters with, e.g., GSM basestations.

It should also be noted that, in the event of using one of the normalpager channels as system channel, it must be seen to that the(standalone) beacon transmitters transmit the ID codes in synchronisedmode. For this purpose, the beacon transmitter should be provided with areceiver which, on the basis of the information packets transmitted bythe transmitters 3, synchronises the beacon transmitter therewith.

FIG. 4 schematically shows a pager which may be used in the abovesystem. The pager, which is located in a car 2, receives various IDcodes together with associated data (IDrec;data) from the transmitter 3and compares it to the ID codes stored in the pager: IDsys—the ID codeof the channel with which, in the pager, ID codes may be set, as aresult of which the pager is activated; IDshared—a collective ID code asa result of which the pager is activated (there may be more of suchcodes: IDshared1, IDshared2 etc.); IDprivate—an individual ID code as aresult of which the pager is activated (of these, too, there may bemore: IDprivate1, IDprivate2 etc.).

The ID codes and data received are normally received from thetransmitter(s) 3. In the system according to the invention, however, thepager in the cars 2 also receives an ID code and “data” from the beacontransmitter 4. The IDsys code is transmitted by said beacontransmitter(s) 4, having as “data” the value of the ID code which isrequired for receiving data relating to the road segment in the vicinityof the beacon transmitter. As soon as a car arrives in the vicinity ofthe beacon transmitter 4, the pager therefore receives IDsys as accesscode and, in the data field, the value for the collective (shared) IDcode (IDshared) with which the pager may be activated later forreceiving data relating to the road section for which the beacontransmitter is responsible. Said road-section-specific data,incidentally, is transmitted by the transmitter 3 and originates from,e.g., a national traffic centre. The local circumstances on the variousroad sections are monitored there and transmitted byroad-section-specific IDshared codes, so that all road users driving onthe same road section, in so far as they are equipped with a pager asdescribed here, be provided with information (data) relating to saidroad section.

The ID codes and data received, as illustrated in FIG. 4, are receivedby a receiver 10 and processed in a control module 11. If the controlmodule detects that the ID code received (IDrec) is equal to the systemID code (IDsys)—whose value is programmed into the control module 11—theassociated data value is interpreted as new ID code (IDshared) on whichthe pager may receive relevant road-section information (“If IDrec-IDsysthen IDshare-data”). If (subsequently) an ID code received is equal toeither said IDshared code or the (programmed, unique) IDprivate code,the associated data is passed on to a display module 12, on which thedata is displayed in (e.g.) alphanumeric form: “if IDrec=IDshare thendisplay data (or) if IDrec=IDprivate then display data”.

FIGS. 5 and 6 show a preferred option of the invention, in which use ismade of beacon transmitters having limited power. In this event, thebeacon transmitters are located on the edges of the information region.The pager in a passing car receives the ID code, in passing, to whichthe pager must be set for receiving information (from transmitters 3)which is relevant to the region (road section) which is entered. In thisoption, use is preferably made of pagers which, using a separatetransmitter 13, receive signals at another frequency (Fpilot) than theone of the carrier wave (Fdata) to which the transmitters 3 transmittheir information (data). Due to the low range of the beacontransmitters 4, they may all make use of the same frequency withoutchancing interference, even with other cordless systems. Each beacontransmitter transmits an ID code (IDpilot) which is equal to the ID codeused by the information transmitters 3 for transmitting data which isrelevant to the region after the beacon transmitter, the regiontherefore which is entered by the passing car. As soon as, in the eventof passing a beacon transmitter, the control unit 11 receives an IDpilotwhich is not equal to the ID code (IDshare) to which the pager washitherto set, the control unit 11 sets the IDshare value in conformitywith said received ID code (IDpilot): “if IDpilot><″” andifIDpilot><IDshare then IDshare=IDpilot″. As may be seen from FIG. 5, inthe event of transition from each region there always are two beacontransmitters, namely, one for one direction of the traffic (from regionA to region B) and one for the other direction (from region B to regionA); after all, for motorists who enter B the pager must be set, by wayof the one beacon transmitter, to the ID code of region B, while thepagers of motorists who enter region A are set, using the other beacontransmitter, to region A. The range and the position of beacontransmitters must therefore be such that they can only affect the pagersin one direction of the traffic. An alternative is offered by the systemshown in FIGS. 7 and 8.

In FIG. 7, at each transition between two adjacent regions or roadsections, there is located only one beacon, transmitter 4. Each beacontransmitter transmits not one but two ID codes at the beacon frequencyFpilot: IDpilot(1), equal to the ID code for the one region, andIDpilot(2), equal to the ID code for the other, adjacent region. Uponreceipt of said two ID codes, the control unit investigates whethereither IDpilot(1) or IDpilot(2) is not equal to the ID code to which thepager had already been set. If in two adjacent regions A and B there arein force ID codes IDA and IDB, the beacon transmitter at the partitionof said regions transmits IDpilot(1)=IDA and IDpilot(2)=IDB. The pagerof a vehicle driving in region A is set to IDshare=IDA. Upon passing theregion boundary, the control unit 11 detects that IDpilot(2)><IDA andsubsequently sets the pager to IDshare=IDpilot(2)=IDB: “for n=1 to 2: ifIDpilot(n)><″” andif IDpilot(n)><IDshare then IDshare=IDpilot(n): nextn″.

The advantage of said option is that the range of the beacontransmitters is not critical, i.e., there need not be taken care thatthe beacon transmitters be only received by pagers in one direction. Onthe contrary, in the present option, pagers must receive thebeacon-transmitter signal in both directions. This in its turn may be adrawback in view of the energy supply to the beacon transmitters. Itwould seem to be a greater drawback, however, that there may be derivedno initial ID code from the beacon transmitters, so that an initial IDcode, e.g., will have to be entered manually.

What is claimed is:
 1. An information system for a traffic network,information of interest to travelers being transmitted by at least oneinformation-transmitter to data receivers in vehicles making use of thetraffic network, the traffic network being broken down into informationregions, said at least one information-transmitter transmittinginformation modules which each relate to an information region, at leastone information module being associated with a region-identificationcode, the information system comprising: a beacon transmitter, in theevent of a vehicle entering an information region, transmitting to thedata receiver in said vehicle a particular region-identification codeassociated with said information region, the data receiver settingitself, using said particular region-identification code from saidbeacon transmitter, to receiving information modules associated withsaid particular region-identification code that are transmitted by saidat least one information-transmitter.
 2. The information systemaccording to claim 1, wherein the beacon transmitter transmits theparticular region-identification code to the data receivers of vehicleswithin the transmission range of said beacon transmitter, the datareceivers setting themselves to receive information modules transmittedby said at least one information-transmitter, which information modulesare associated with the particular region-identification codetransmitted by the beacon transmitter.
 3. The information systemaccording to claim 1, wherein the beacon transmitter transmits theparticular region-identification code to the data receivers of vehiclespassing the beacon transmitter, whereupon the data receiver sets itselfto receive information modules transmitted by the at least oneinformation-transmitter, which information modules are associated withthe particular region-identification code transmitted by the beacontransmitter.
 4. The information system according to claim 2, wherein theregion-identification code is transmitted by the beacon transmitter byway of the same medium (Fdata) as the one with which the said at leastone information-transmitter transmits the information modules.
 5. Theinformation system according to claim 2, wherein theregion-identification code is transmitted by the beacon transmitter byway of another medium (Fpilot) than the medium (Fdata) by way of whichthe said at least one information-transmitter transmits the informationmodules.
 6. The information system according to claim 3, wherein eachbeacon transmitter transmits only the particular region-identificationcode of the region which is entered by passing vehicles, furthercomprising: a control unit setting the data receiver in such a vehiclein conformity with the particular region-identification code receivedfrom the beacon transmitter.
 7. The information system according toclaim 3, wherein each beacon transmitter transmits the particularregion-identification codes of both adjacent regions comprising theregion just left and the region entered, further comprising: a controlunit setting the data receiver of a passing vehicle in conformity withthe value of the particular region-identification code, which is notequal to the region-identification-code setting of said data receiver.8. The information system according to claim 3, the particularregion-identification code being transmitted by the beacon transmitterby way of the same medium (Fdata) as the one with which the said atleast one information transmitter transmits the information modules. 9.An information system for a traffic network having information regions,comprising: at least one information-transmitter that transmits modulescomprising information of interest to travelers, each module beingassociated with an information region and being associated with aregion-identification code; a data receiver in a vehicle making use ofthe traffic network; and at least one beacon transmitter that transmitsa particular region-identification code of one of said informationregions when a vehicle enters that information region to the datareceiver in said vehicle, wherein the data receiver sets itself, usingsaid particular region-identification code, to receiving modulesassociated with said particular region-identification code from said atleast one information-transmitter.
 10. The information system accordingto claim 9, wherein the beacon transmitter transmits the particularregion-identification code to data receivers of vehicles within thetransmission range of said beacon, and the data receiver receivesmodules transmitted by said at least one information-transmitter, themodules being associated with the particular region-identification codetransmitted by the beacon transmitter.
 11. The information systemaccording to claim 9, wherein the beacon transmitter transmits theregion-identification code to the data receiver when the vehicle passesthe beacon transmitter, and the data receiver sets itself to listen tomodules transmitted by the at least one information-transmitter whichare associated with the particular region-identification codetransmitted by the beacon.
 12. The information system according to claim10, wherein the particular region-identification code is transmitted bythe beacon transmitter by way of the same medium as the said at leastone information-transmitter that transmits the modules.
 13. Theinformation system according to claim 10, wherein the beacon transmittertransmits the particular region-identification code by way of anothermedium different from the medium used by said at least oneinformation-transmitter that transmits the modules.
 14. The informationsystem according to claim 11, wherein each beacon transmitter transmitsonly the particular region-identification code of the information regionthat is entered by passing vehicles, further comprising: a control unitto set the data receiver in such a vehicle in conformity with theparticular region-identification code received from the beacontransmitter.
 15. The information system according to claim 11, whereineach beacon transmitter transmits the particular region-identificationcodes of at least two adjacent regions, further comprising: a controlunit to set the data receiver of a passing vehicle in conformity withthe value of the particular identification code, which is not equal tothe region-identification code setting of said data receiver.
 16. Theinformation system according to claim 11, the region-identification codebeing transmitted by the beacon transmitter by way of the same medium assaid at least one information-transmitter that transmits the modules.17. The information system of claim 1 wherein the beacon transmitter islocated terrestrially.
 18. The information system of claim 9 wherein aparticular region-identification code is set by a transmission from onebeacon transmitter.
 19. The information system of claim 9 wherein eachbeacon transmitter transmits one region-identification code.
 20. Theinformation system of claim 9 wherein the at least one beacontransmitter is located terrestrially.
 21. The information system ofclaim 9 wherein a particular region-identification code is set by atransmission from one beacon transmitter.
 22. The information system ofclaim 9 wherein each beacon transmitter transmits oneregion-identification code.